Manage your subscription

Impurity blamed for food supplement deaths

23 November 1991

By
DAN CHARLES in
WASHINGTON DC

The fatal ingredient of a nutritional supplement that was responsible
for 27 deaths and 1500 cases of serious illness in 1990, has been identified
as a contaminant called EBT. The finding by researchers at the US National
Institutes of Health will allay fears that the genetically engineered bacteria
used to manufacture the food supplement, L-tryptophan, might have been to
blame. However, the scientists also found that L-tryptophan itself, while
not immediately fatal, may damage the pancreas.

According to Samuel Page of the US Food and Drug Administration, EBT
was formed when acetaldehyde, a common chemical that is produced when ethanol
oxidises, reacted with L-tryptophan. The manufacturer, the Japanese company
Showa Denko, could have removed the EBT with a simple charcoal filter, said
Page.

People who ate Showa Denko’s L-tryptophan suffered severe muscle pain
and weakness, hardening of the skin and nerve damage. The number of white
blood cells called eosinophils increased. Experiments carried out by Esther
Sternberg of the NIH, linked all these phenomena with EBT.

When Lori Love of the FDA fed Showa Denko’s product to rats, it produced
a swelling of the fascia, the connective tissue that lies just under the
skin and between muscles. EBT alone produced similar results, causing the
fascia to swell to twice its normal size. Rats eating pure L-tryptophan,
without EBT, showed only a tiny thickening of the fascia. Love says that
other impurities in L-tryptophan might also play a role in causing illness,
but no experiments have yet been carried out on them.

Advertisement

Sternberg’s experiments also suggest that pure L-tryptophan might be
harmful. All the rats, including those eating pure L-tryptophan, showed
scarring of the pancreas. In addition, says Page, people who drink alco
hol while taking L-tryptophan could form toxic EBT in their bodies, as both
of the necessary chemicals would be present. Although L-tryptophan is a
natural amino acid, says Page, it is present in the body as part of larger
proteins, and almost never in the free form that was sold as a food supplement.

According to Page, L-tryptophan will be regulated as a drug in the future,
rather than as a food supplement. Winning approval to sell it as a drug
would take several years.